Method for deferred location reporting in a radio cellular network

ABSTRACT

The invention relates to the provision of deferred location reporting wherein the reporting is triggered by a trigger location change event. Trigger location change events are either related to a user of a cellular telecommunication network entering, leaving or changing an area, or to an area, which is entered or left by a user.

TECHNICAL AREA

[0001] The invention relates to methods, a node and a user equipment fordeferred reporting of a location of a user of a cellulartelecommunication network to a client.

PRIOR ART

[0002] Location reporting is used for providing a client withinformation about the location of a user. For a client, for example acharging subsystem, emergency services, user equipment of the user orlocation services, it is necessary to know the location of a user.

[0003] One way to implement location reporting is described in the 3GPPTechnical Specification TS 25.305 Version 5.4.0, published March 2002.It describes direct location reporting by using a cell identifier,forced state transition of user equipment and the transforming of cellidentification into geographical coordinates in a radio networkcontroller.

[0004] The 3GPP Technical Specification TS 23.271 Version 5.2.0published March 2002 describes how direct location reporting can beimplemented by using positioning methods. Said positioning methods arebased for example on GPS (Global Positioning System), cellidentification, observed time difference of arrival, or E-OTD (EnhancedObserved Time Difference).

[0005] The 3GPP specification TS 122 071 version 3.3.0 of October 2000introduces deferred location reporting. However, it lacks a descriptionof how to implement it.

[0006] The international patent application WO99/52316 published onOctober 14 of 1999 describes a method and a system for exploitinglocation dependent services in a cellular radio system. To that end itis described that user equipment is enabled to determine its location bymeans of determining the base transceiver station it is served by or thecell it is located in. However, the provision of its location to aclient is not disclosed.

[0007] Thus, neither document of prior art describes how to implementdeferred location reporting in a way that a location of a user isprovided by means of geographical data to a client external to thenetwork.

[0008] Therefore it is object of the invention to overcome theshortcomings of the prior art.

[0009] This is solved by the method of claim 1 and the user equipment ofclaim 11.

[0010] It is advantageous to define at least one trigger location changeevent for initiating a deferred location report. This allows keepinglocation information about a user up to date for at selectablegranularity.

[0011] Further advantageous embodiments can be derived from thedependent claims.

[0012] Advantageous is the choice for the trigger location change eventbetween the change, an entering, or a leaving of one an area served by amobile services switching centre, a serving General Packet Radio Servicesupport node, a cell, a location area, a routing area, or a service areaaccording to claim 2. This enables to select an optimal compromisebetween accuracy and signalling effort.

[0013] Also advantageous is the execution of a positioning methodaccording to claim 3. This allows determining the location of a userwith a high accuracy.

[0014] Further advantageous is the dedication of accuracy of locationinformation by the user according to claim 4. This allows the user toinfluence the level of information provided to a client.

[0015] Also advantageous is the monitoring and detecting of a triggerlocation change event by user equipment according to claim 5. Thisreduces the implementation effort of the invention as the triggerlocation change events are already detected in existing user equipmentfor cellular telecommunication systems. It furthermore reduces thesignalling effort in the case that the user of the user equipmentchanges from one mobile services switching centre to another mobileservices switching centre as no indication that location reporting isactivated for the user has to sent between mobile services switchingcentres. Further advantageous is the monitoring and detecting of atrigger location change event by user equipment according to claim 6.This reduces the implementation effort of the invention as the triggerlocation change events are already detected in some nodes of cellulartelecommunication systems and it does not require a modification of userequipment.

[0016] Advantageous is the storing of an indicator that a triggerlocation change event is defined for a subscriber according to claim 7.This avoids the loss of information about deferred location requests ata hand-over.

[0017] Further advantageous is the dependence on a user's permission toprovide location information according to claim 8. This secures theprivacy of a user.

[0018] Advantageous is the definition of a trigger location change eventas the entering or leaving of a particular predefined area according toclaim 9. This allows monitoring predefined areas instead of predefinedusers.

SUMMARY OF THE INVENTION

[0019] The invention introduces a method for deferred provision oflocation information of a user of a cellular telecommunication networkto a client. The method comprises the steps of defining or receiving adefinition of at least one trigger location change event for a user,receiving from a client a request for provision of deferred locationinformation for the user, monitoring said trigger location change eventfor said user, detecting the occurrence of the trigger event,determining the location of the user, and providing the location of theuser to the client.

[0020] A trigger location change event is a change, an entering, or aleaving of one an area served by a mobile services switching centre, aserving General Packet Radio Service support node, a cell, a locationarea, a routing area, or a service area.

[0021] The step of determining the location of the user can comprise theexecution of a positioning method. Positioning methods are known fromthe technical specifications cited under prior art.

[0022] If location information of a user is related to a structure ofthe cellular telecommunication network, for example by giving anidentification of a cell, a service area, a location area, an areaserved by a mobile services switching centre, or an area served by aGPRS support node, it can be transferred into location informationrelated to geographical coordinates. An example for this is given underprior art, wherein a radio network controller transforms cellidentification into geographical coordinates.

[0023] The user may dedicate the accuracy of location informationprovided to the client.

[0024] In an embodiment of the invention, the user equipment performsthe monitoring and detecting of a trigger location change event andinitiates the provision of the location to the client, but this can bealso performed by a node of the cellular telecommunication network.

[0025] If a network node performs the monitoring and determining, anindicator that a trigger location change event is defined for thesubscriber is stored in a node, storing subscriber data.

[0026] An additional step of verifying that the user granted apermission to provide the client with location information can beexecuted.

[0027] The trigger location change event can be the entering or leavingof a particular predefined area. This trigger can be set independentfrom any user, related only to the selected area. Additional to thelocation information, information about the velocity of a user whenentering or leaving the particular predefined area can be provided tothe client.

[0028] If the monitoring and detection of a trigger location changeevent is performed by a node of the cellular telecommunication network,said node comprises means for monitoring whether a change an entering,or a leaving of one an area served by a mobile services switchingcentre, a serving General Packet Radio Service support node, a cell, alocation area, a routing area, or a service area, occurred.

[0029] If the monitoring and detection of a trigger location changeevent is performed by user equipment for communicating in a cellulartelecommunication network, said user equipment comprises means formonitoring whether a change an entering, or a leaving of one an areaserved by a mobile services switching centre, a serving General PacketRadio Service support node, a cell, a location area, a routing area, ora service area, occurred. It furthermore comprises means for initiatinga determining of the location of the user equipment.

BRIEF DESCRIPTION OF THE FIGURES

[0030]FIG. 1 depicts a signal flow according to the invention for acircuit switched cellular telecommunication network,

[0031]FIG. 2 depicts a signal flow according to the invention for apacket switched cellular telecommunication network.

DETAILED DESCRIPTION OF THE INVENTION

[0032] In the following the invention is described in more detail bymeans of embodiments and figures.

[0033] Cellular telecommunication networks store information about thelocation of a user in order to ensure the availability of a user. Thisinformation can be used for location information that is requested by aclient as well. A client may be for example a charging system orsubsystem, a provider of location services, user equipment or anemergency call centre.

[0034] In a radio access network of a cellular telecommunicationnetwork, the location of a mobile is known in different granularity,depending of the type of radio access network and the mobile connectedstate. The granularity of location information kept in the network forroaming subscribers is a trade off between saving cell updates and thenumber of paging messages to be sent. In signalling connected mode thegranularity is the cell, where the mobile is connected.

[0035] During roaming of a user of the telecommunication network, thelocation is kept as location area in an mobile services switching centrefor a circuit switched connected user and as routing area in a servingGPRS support node for a packet switched connected user.

[0036] During an active connection, in telecommunication networksoperating according to UMTS (Universal Mobile Telecommunication System)standards, after the reception of a RAB (Radio Access Bearer) assignmentresponse, the radio network controller knows the cell and the servicearea.

[0037] In GSM, during an active connection after an assignment responsehas been received, the base station controller knows the cell.

[0038] Information about the location of a user is certainly availablewith a lower accuracy than the mentioned granularity, for exampleimplicitly by an identification of a node currently serving the user asfor example a mobile services switching centre, a GPRS support node, aradio network controller, or a base station controller. From the nodeidentification together with knowledge about the structuring of thenetwork, i.e. the area served by the respective node, the location ofthe user can be determined.

[0039] The accuracy or granularity of the location information candepend on requirements of the client, privacy requirement of the user,available location information, processing and signalling effort todetermine the location information, legal requirements, and alike.

[0040] As the information about areas associated to a certain node orthe place and extension of a cell, a routing area, a location area and aservice area is usually available only within the cellulartelecommunication network, it is not significant for an external client.

[0041] To overcome this problem, two solutions are suggested:

[0042] The client is provided with a database for mapping anidentification of a node, a cell, a routing area, a location area, or aservice area to geographical coordinates. This database contains a tableof identifications allocated to either the actual coordinates describingthe respective area or at least one point and a radius that include thearea.

[0043] If the operator does not want to provide information about thestructuring of his network, the mapping of identification to area isdone within the network.

[0044] The provision of deferred location reports is performed eitherfor a certain time, indicated by a timer value or until the clientterminates his request. To make sure that the provision of locationinformation is continued even if a mobile services switching centre orserving GPRS support node change for the user occurred, the mobileservices switching centre or respectively the serving GPRS support nodesignals to the gateway mobile location centre the change. The gatewaymobile location centre determines the new mobile services switchingcentre or respectively the new serving GPRS support node and restartsthe request for location information for the user.

[0045] In the following the invention is described in more detail bymeans of a so-called 3^(rd)-generation-network comprising a corenetwork, a UTRAN (UMTS Terrestrial-Radio Access Network) and a GERAN. AGERAN is a GSM (Global System for Mobile telecommunication)-EDGE(Enhanced Data rates for GSM Evolution) Radio Access Network.

[0046] The 3^(rd)-generation-network keeps track of the subscriber'slocation. After assigning a RAB (Radio Access Bearer) for a user, UTRANknows the location of the user on cell level. The cell is mapped to aservice area. A service area stands for a geographical area, but it isdecoupled from the cell structure to keep the physical information aboutthe cell structure in UTRAN.

[0047] The core network uses the ‘Location Reporting Control’ and‘Location Report’ RANAP (Radio Access Network Application Protocol)messages to get location information from UTRAN/GERAN over an Iuinterface from a radio network controller of the access network. Themessages are defined in the 3GPP technical specification TS 25.413,Version 5.0.0, published March 2002.

[0048] ‘Perform Location Request’ and ‘Perform Location Response’ BSSMAP(Base Station System Management Application Part) messages are usedtowards the GERAN over an A interface between a mobile servicesswitching centre and a base station controller. The messages as definedin the 3GPP technical specification TS 48.008, Version 5.4.0, publishedFebruary 2002, are modified in so far as that they permit the requestand accordingly the provision of location information not exclusively asgeographical coordinates but also as information related to a structureof the cellular telecommunication network.

[0049] The core network requests the radio access networks to sendlocation information when a user changes, enters or leaves a servicearea.

[0050] Location Report, Location Reporting Control, Perform LocationRequest and Perform Location Response are connection-oriented messagesthat can be used to receive location information. In order to gaininformation about the location of a user, the user must have an activesignalling connection towards the cellular telecommunication network.

[0051] User equipment in GPRS has three different states IDLE, READY andSTANDBY. Only in READY state an active signalling connection isestablished. After user equipment attaches its state changes fromSTANDBY to READY. It stays in READY state for a predefined timer value.When the timer value expires, the mobile changes from READY to STANDBY.The timer value can be set by the SGSN or by user equipment. It can beset to infinity, so that user equipment stays in the READY mode.

[0052] Several mechanisms exist to ensure that location informationabout a user can be derived at a required accuracy level.

[0053] A mobile in READY state moving between cells within the same SGSNrouting area updates its SGSN with its location by sending a cell updatepacket. In a STANDBY state a mobile moving between cells within the samerouting area does not send a cell update packet. Thus, if location of auser is required with accuracy more precise than routing area level,user equipment has to be kept in READY state.

[0054] Furthermore, as described in the 3GPP technical specification TS25.305 Version 5.4.0, it is possible to force a change of state of userequipment from IDLE, i.e. a state without an active signallingconnection, to READY state.

[0055] In the case that the trigger location change event is the changeof a service area, the RANAP message Location Request or LocationReporting Control with the existing parameter ‘inform on changes ofservice area’ can be used. In that case, the radio network controllerwill inform the mobile services switching centre or the serving GPRSsupport node, whichever sent the Location Reporting Control of LocationRequest message, of every change of service area by the user. If theuser moves from an area served by the radio network controller to anarea served by another radio network controller, the message is sent tothe new radio network controller for the continuation of the service. Aservice area at which a user is currently located can be determined if aPDP (Packet Data Protocol) context is established. As long as a PDPcontext is established, user equipment stays in a connected mode.

[0056] In a network operating according to GSM standards, it is alwayspossible to track a change of a cell for a user.

[0057] The reporting of a location is not only possible on a per userbase, that is that the location of a predefined user is reported, butalso on a per area base. This means that a client can request that hereceives an indication, whenever a user enters or leaves a particularpredefined area, for example a service area, a location area, a routingarea, a cell, an area served by an mobile services switching centre or aGPRS support node. This new kind of location report is interesting forexample for location services or for charging purposes. The new servicecan be implemented for example by updating the interface between theclient and the gateway mobile location centre and the interface betweengateway mobile location centre and serving GPRS support node or mobileservices switching centre. This can be implemented for example byintroducing a new parameter in the RANAP Location Reporting Controlmessage. In an embodiment of the invention, information about the speedof the user is sent together with location information when a subscriberenters or leaves the particular predefined area. The information aboutthe velocity of the user can be used for traffic predictions andcharging purposes. For example if a user enters an already congestedarea he may be subject of paying an extra fee.

[0058] Furthermore it is possible to track if a user moves from a firstpredefined area to a second predefined area, that is, if he crosses aborder between two predefined areas. This can be implemented for exampleby transmitting and checking of two locations for a user. An area is arouting area, a location area, a service area, a cell, or an area servedby a mobile services switching centre or a GPRS support node.

[0059] In the following the invention is described by means of FIG. 1.

[0060]FIG. 1 depicts a cellular telecommunication network comprising aradio network controller RNC, a mobile services switching centre MSC,and a gateway mobile location centre GMLC. The gateway mobile locationcentre GMLC is connected to a client C2. The client C1 sends in a firststep 11 a LCS (Location Service) request message comprising parametervalues identifying a user, demanding that a deferred location report forthe user is requested, and that the trigger location change event ischange of routing area. In a further embodiment of the invention themessage also comprises a parameter with a parameter value that indicateswhether the location shall be provided by geographical coordinates or byinformation related to the structure of the cellular telecommunicationnetwork.

[0061] In a further embodiment of the invention, the first step 11 maybe performed by user equipment instead of the client C1. Therefore tanidentification, for example an IMSI (International Mobile SubscriberIdentification) is transmitted by DTAP signalling for mobile originatinglocation request that is modified as described above. In the embodimentwhere the user equipment of the monitored user is the client, privacymeasures can be omitted. Alternatively the user equipment may be enteredas a client in the SLPP.

[0062] The gateway mobile location centre GMLC receives the message andtransforms it in a next step 12 into a Provide Subscriber Locationmessage comprising parameter values identifying a user, demanding that adeferred location report for the user is requested, and that the triggerlocation change event is change of routing area. The message is asdefined in the 3GPP technical specification TS 29.002, version 5.1.0published March 2002, is adapted accordingly so that it can carry thebefore mentioned information. Therefore the parameter LCS QoS (Qualityof Service) specifying the response time and the accuracy of thelocation request is modified that it indicates that the LCS client canindicate the capability to recognize also the Location information innon-geographical coordinates format, i.e. mobile services switchingcentre number, serving GPRS support node number, location area, routingarea, service area or cell identity. The gateway mobile location centreGMLC sends the message to the mobile services switching centre MSC.

[0063] The mobile services switching centre MSC receives the ProvideSubscriber Location message in a next step 13. It transforms it into alocation report control message that comprises an identification of thetrigger location change event. In a further embodiment of the inventionthe message also comprises a parameter with a parameter value thatindicates whether the location shall be provided by geographicalcoordinates or by information related to the structure of the cellulartelecommunication network. The mobile services switching centre MSCsends the location report control message to the radio networkcontroller RNC.

[0064] The radio network controller RNC monitors the user whether itchanges the service area or not. When the radio network controller RNCdetects a change of service area of the user, it sends a location reportmessage in a next step 14 to the mobile services switching centre MSC.The location report message comprises an identification of the newservice area in which the user is currently located. In an alternativeembodiment of the invention the radio network controller RNC transformedthe identification of the service area into geographical coordinates.

[0065] The mobile services switching centre MSC receives the locationreport message and forwards the location information in a SubscriberLocation Report message together with an identification of the user tothe gateway mobile location centre GMLC in a next step 15. The locationinformation is sent as an identification of the service area in whichthe user currently is located. In an alternative embodiment the locationinformation is sent as geographical coordinate.

[0066] The gateway mobile location centre GMLC receives the message. Ittransforms the identification of the service area into geographicalcoordinates and forwards the location information for the user in a LCSService Response message to the client C1 together with anidentification of the user. In an alternative embodiment of theinvention the client C1 receives the identification of the service area.

[0067] In an embodiment of the invention, the location information isset to the user equipment as a client.

[0068]FIG. 2 depicts a cellular telecommunication network comprising aradio network controller RNC2, a serving GPRS support node SGSN, and agateway mobile location centre GMLC2. The gateway mobile location centreGMLC2 is connected to a client C2.

[0069] The client C2 sends in a first step 21 a LCS (Location Service)request message comprising parameter values identifying a user,demanding that a deferred location report for the user is requested, andthat the trigger location change event is change of routing area. In afurther embodiment of the invention the message also comprises aparameter with a parameter value that indicates whether the locationshall be provided by geographical coordinates or by information relatedto the structure of the cellular telecommunication network.

[0070] In a further embodiment of the invention, the first step 21 maybe performed by user equipment instead of the client C1. In theembodiment where the user equipment is the client, privacy measures canbe omitted for the user equipment as the client. Alternatively the userequipment may be entered as a client in the SLPP.

[0071] The gateway mobile location centre GMLC2 receives the message andtransforms it in a next step 22 into a Provide Subscriber Locationmessage comprising parameter values identifying a user, demanding that adeferred location report for the user is requested, and that the triggerlocation change event is change of routing area. In a further embodimentof the invention the message also comprises a parameter with a parametervalue that indicates whether the location shall be provided bygeographical coordinates or by information related to the structure ofthe cellular telecommunication network. The gateway mobile locationcentre GMLC2 sends the message to the serving GPRS support node SGSN.

[0072] The serving GPRS support node SGSN receives the ProvideSubscriber Location message in a next step 23. It transforms it into alocation report control message that comprises an identification of thetrigger location change event. In a further embodiment of the inventionthe message also comprises a parameter with a parameter value thatindicates whether the location shall be provided by geographicalcoordinates or by information related to the structure of the cellulartelecommunication network. The serving GPRS support node SGSN sends thelocation report control message to the radio network controller RNC2.

[0073] The radio network controller RNC2 monitors the user whether itchanges the service area or not. When the radio network controller RNC2detects a change of service area of the user, it sends a location reportmessage in a next step 24 to the serving GPRS support node SGSN. Thelocation report message comprises an identification of the new servicearea in which the user is currently located. In an alternativeembodiment of the invention the radio network controller RNC2 transformsthe identification of the service area into geographical coordinates.

[0074] The serving GPRS support node SGSN receives the location reportmessage and forwards the location information in a Subscriber LocationReport message together with an identification of the user to thegateway mobile location centre GMLC2 in a next step 25. The locationinformation is sent as an identification of the service area in whichthe user currently is located. In an alternative embodiment the locationinformation is sent as geographical coordinate.

[0075] The gateway mobile location centre GMLC2 receives the message. Ittransforms the identification of the service area into geographicalcoordinates and forwards the location information for the user in a LCSService Response message to the client C2 together with anidentification of the user. In an alternative embodiment of theinvention the client C2 receives the identification of the service area.

[0076] In an embodiment of the invention the user equipment can act as aclient and receives the location information either as an identificationof an area or a geographical coordinates.

[0077] In general, the mapping of this location information togeographical coordinates can be done in any of the nodes involved, forexample in the base station controller, radio network controller, mobileservices switching centre, serving GPRS support node, home locationregister, home subscriber server or gateway mobile location centre.

[0078] The clients C1 or C2 use an identification of a service area forexample to filter all users who are entering a particular service area.Such information may be used for traffic calculations or advertisingpurposes.

[0079] The client C1, C2 indicates the minimum accepted accuracy for therequested application in its LCS Service Request. This can beimplemented by a new parameter in the existing MAP message ProvideSubscriber Location, wherein the parameter indicates the lowestacceptable accuracy. For the user, a profile is stored, for example inthe SLPP (Subscriber LCS Privacy Profile). The existing SLPP is expandedin a way that it comprises a new parameter with a parameter valuedescribing the maximum accepted accuracy for the user on a per clientbasis. The new parameter value can be set by the existing MAP operationInsert Subscriber Data.

[0080] During the LCS privacy checks, an involved mobile servicesswitching centre or serving GPRS support node verifies the maximumaccepted accuracy by the subscriber for that client and the minimumaccepted accuracy by the client.

[0081] If the maximum allowed accuracy by the subscriber is greater thanor equal to the minimum accepted accuracy by the LCS client, the requestis accepted. For the execution of the comparison and the selection ofthe determining of the location information, an accuracy given as anabsolute distance is mapped. This mapping is performed according to apredefined table. The operator can predefine such tables for eachservices switching centre or serving GPRS support node, taking intoaccount the respective topology of the network at the mobile servicesswitching centre or serving GPRS support node. An example is given inthe table below: Requested accuracy Determining of location informationby (K code) 0-500 meters Positioning method 500-2000 meters Cell orservice area identification 2000-4000 meters Location area or servicearea identification 4000-180000 meters Mobile services switching centreor serving GPRS support node identification

[0082] A node as for example a radio network controller, a mobileservices switching centre or a serving GPRS support node that is tomonitor a trigger location change event comprises means for detectingsaid event. This means may be implemented by software, hardware or acombination of both.

[0083] A user equipment that is to monitor a trigger location changeevent comprises means for detecting said event. This means may beimplemented by software, hardware or a combination of both.

1. Method for deferred provision of location information of a user of acellular telecommunication network to a client external to the network,wherein the method comprises the steps of: defining (11, 21) orreceiving a definition of at least one trigger location change event fora user, receiving (12, 22) from the client (C1) a request for a deferredprovision of deferred location information for a user, monitoring (13,23) said trigger location change event for said user, detecting (14, 24)the occurrence of the trigger event, determining (15, 25) the locationof the user, transforming location information of a user related to astructure of the cellular telecommunication network into locationinformation related to geographical coordinates, and providing (16, 26)the location of the user to the client.
 2. Method according to claim 1,wherein a trigger location change event is a change, an entering, or aleaving of one of an area served by a mobile services switching centre,a serving General Packet Radio Service support node, a cell, a locationarea, a routing area, or a service area.
 3. Method according to any ofthe preceding claims, wherein the determining of the location of theuser comprises the execution of a positioning method.
 4. Methodaccording to any of the preceding claims, wherein the user dedicates theaccuracy of location information provided to the client.
 5. Methodaccording to any of the preceding claims, wherein equipment of the userperforms the monitoring and detecting of a trigger location change eventand initiates the provision of the location to the client.
 6. Methodaccording to any of the preceding claims, wherein a node of the cellulartelecommunication network performs the monitoring and detecting of atrigger location change event and initiates the provision of locationinformation to the client.
 7. Method according to claim 6, wherein anode performing home location register functions stores an indicatorthat a trigger location change event is defined for the subscriber. 8.Method according to claim 6 or 7, with the additional step of verifyingthat the user granted a permission to provide the client with locationinformation.
 9. Method according to any of the preceding claims, whereinthe trigger location event is defined as an entering or leaving of aparticular predefined area.
 10. Method according to claim 9, whereininformation about the velocity of a user when entering or leaving theparticular predefined area is provided to the client.
 11. User equipmentfor communicating in a cellular telecommunication network characterisedby means for monitoring whether a change, an entering, or a leaving ofone of an area served by a mobile services switching centre, a servingGeneral Packet Radio Service support node, a cell, a location area, arouting area, or a service area occurred, and means for initiating adetermining of the location of the user equipment.